The use of at least two timing devices, which each has its own initially calibrated time base, has become necessary for timing important sports competitions, such as for example, ski races. The two timing devices operate independently of each other, but receive the same race start pulse supplied by the same start gate. The timing devices also receive the same stop pulse for the timing of a race as soon as the competitor crosses the finish line. The race times of the two timing devices can be stored in a known way for each competitor. Moreover, the time of one or several races, particularly of the main device, can be displayed on a display screen, which may be visible to spectators.
For both timing devices, only one calibration is performed for each time base, initially, for example, in the factory before the timing system is used for the proper conduct of the sports competition. The operation of the two timing devices, which may be arranged in the same timing system apparatus, ensures continuity of timing in the event that one of the devices fails. However, throughout the sports competition, the time bases of the two devices may vary slightly. This may result in two time measurements rounded off to a hundredth or thousandth of a second, which are different. This is therefore a drawback of this type of timing system, which has to guarantee a high level of timing precision.
EP Patent No. 1 139 299 A1 may be cited, which discloses a radio transmission timing system. The system includes several peripheral units, each provided with a time base and a radio signal transmission means. The peripheral units are arranged at different places on the course or track of a sports competition in order to take a start time, intermediate times and a finish time for each competitor. Time shiftings between said units are unavoidable given that they are arranged remote each other. The time bases of each unit have to be synchronised relative to each other by radio or GPS signals. This requires an imposing infrastructure in order to ensure proper synchronisation of each unit for measuring the different times of the sports competition, which constitutes a drawback.